Effect of Winter Grazing Management of Stockpiled Native Pastures of Basaltic Soils of Uruguay on Daily Gains of Heifers

The effect of three grazing systems of fall stockpiled native pastures on the winter gains of 66 Hereford heifers (135 kg) was studied. Treatments were: continuos grazing (CG); (C7) the plot was divided in 12 and each was grazed for 7 days and (C28), the plot was divided in 3 and each were grazed for 28 days. Heifers were weighed every 14 days and grazing behaviour was recorded. Stockpiled HM was greater (P\u3c 0.05) in C7 and C28 than in CG (988, 912, and 604 kg DM/ha, respectively). Herbage allowance (HA) was greater (P\u3c 0.01) in CG followed by C28 and C7 (11.7, 6.6 and 5.9 kg DM/100 kg LW, respectively). Post-grazing HM was greater (P0.05) in all pastures (CP 10.2%, NDF 71.2%, ADF 41.3% and ash 14.4%). Final LW of heifers were similar (P\u3e 0.05) (167, 162 and 160 kg for CG, C7 and C28, respectively). A very mild winter favoured exceptional gains which tended to be higher in CG (0.353 kg/day) than in C7 (0.305 kg/day) and C28 (0.278 kg/day). Grazing time was greater (P\u3c 0.05) in CG and bite rate was lower in C28 than in C7 and CG heifers. Grazing management did not affect daily gains. Nevertheless, total remaining HM in C28 and more so in C7 more than doubled that in CG, where more animals could have grazed with increasing total productivity

A Sheep and Catlle Diet Selection Study on a Fertilized Native Sward in Uruguay

This study was undertaken during winter, spring and summer 1997, located in the basaltic region of Uruguay to evaluate the effects of stocking rate (SR) and N and P fertilizer application on sward characteristics and on sheep and cattle diet selection and grazing behaviour. The treatments applied were: a) control (C; without fertilizer application using a SR of 0.9 stock units (SU)/ha), b) T1 (with N and P fertilizer application using a SR of 0.9 SU/ha), c) T2 (with N and P fertilizer application using a SR of 1.2 SU/ha) and d) T3 (with N and P fertilizer application using a SR of 1.5 SU/ha). In general, compared with C, fertilized treatments resulted in increments in sward surface height (SSH) and sheep bite weight (BW): a) winter (3, 8, 5 and 5 cm., P \u3c 0.01; 79, 142, 139 and 92 mg DM/bite, P \u3c 0.05), b) spring (3, 8, 5 and 6 cm., P \u3c 0.01; 108, 188, 115 and 215 mg DM/bite, P \u3c 0.01), and c) summer (7, 14, 11 and 8 cm., P \u3c 0.01;146, 199, 182 and 131 mg DM/bite, P \u3c 0.05) for C, T1, T2 and T3, respectively. In general, the nutritive value of diet selected by sheep and cattle was higher than that of the pasture on offer, and higher in sheep than in cattle: a) winter (17, 18 and 16% crude protein, CP, P \u3c 0.05; 39, 37 and 41% acid detergent fiber, ADF, P \u3c 0.05), b) spring (11, 14 and 11% CP, P \u3c 0.05; 42, 33 and 37% ADF, P \u3c 0.01), and c) summer (8, 10 and 9% CP, P \u3c 0.05; 50, 40 and 45% ADF, P \u3c 0.01) for pasture on offer, sheep and cattle diets, respectively. This study demonstrated the importance of fertilizing native swards to improve production, structure, nutritive value, and animal carrying capacity and animal performance. It also shows the important role that diet selection plays in determining the nutritive value of the forage eaten by sheep and cattle, and stresses the greater selective ability of sheep over cattle

A Comparative Grazing Study of Sheep and Cattle Diet Selection on Native Pastures in Uruguay

An experiment was carried out during winter, spring and summer 1997, on native pastures of the basaltic region of Uruguay to evaluate the effects of different herbage mass levels (high, medium and low) on sward characteristics and on sheep and cattle diet selection and grazing behaviour. Higher herbage masses resulted in increments in herbage accumulation and sheep bite weight: winter (1880, 1513 and 610 kg DM ha-1, P \u3c 0.01; 199, 148 and 128 mg DM/bite, P \u3c 0.01), and summer (3046, 2175 and 1172 kg DM ha-1, P \u3c 0.01; 214, 175 and 143 mg DM/bite, P \u3c 0.01) for high, medium and low herbage mass levels respectively. The nutritive value of diet selected by sheep and cattle was higher than that of the herbage on offer, and higher in sheep than in cattle: winter (10.2, 15.9 and 12.5% crude protein, CP, P \u3c 0.05; 49.2, 32.4 and 38.1% acid detergent fiber, ADF, P \u3c 0.01, and summer (7.4, 10 and 9.5% CP, P \u3c 0.05; 51.1, 36.8 and 43% ADF, P \u3c 0.01) for herbage on offer, sheep and cattle diets respectively. These contrasting results found in the nutritive value were closely associated with differences in the proportions of the botanical components recorded, particularly the differential contribution of dead material. This experiment quantified the importance of diet selection in determining the nutritive value of the forage eaten by sheep and cattle on the native pastures of the basaltic region of Uruguay and established some relationships between diet selection and grazing management, involving animal selectivity ability differences (sheep versus cattle) and seasonal effects

Produção e qualidade de silagens de híbridos de milho (Zea mays) e de híbridos de sorgo (Sorghum bicolor) Forage production and quality of corn (Zea mays) and sorghum (Sorghum bicolor) hybrids silage

Com o objetivo de avaliar a produção e a qualidade de cinco híbridos de milho (Zea mays) e três híbridos de sorgo (Sorghum bicolor), foi conduzido um experimento no Departamento de Zootecnia, UFSM. O delineamento experimental foi de blocos casualizados com três repetições. Os tratamentos foram: híbridos de milho - Pioneer 3072 (P 3072), Agroceres 211 (AG 211), Cargill 525 (C 525), Pioneer 3232 (P 3232) e Agroceres 213 (AG 213); sorgo -todos os híbridos foram da Agroceres: AG 2004E, AG 2002 e AG 2005E. A população estabelecida foi de 50.000 e 160.000 plantas/ha para milho e o sorgo, respectivamente. As plantas foram cortadas a 15cm do solo, quando atingiram o estádio de grão farináceo. Posteriormente, os híbridos foram picados e ensilados em vidros vedados, colocados em tubos de concreto e tapados com o material verde restante. Com relação à produção de Matéria Seca, o híbrido P 3072 destacou-se em relação aos demais, sendo superior (P<0,05) ao AG 213 e aos três híbridos de sorgo. Para as variáveis de qualidade da silagem, houve diferença significativa (P<0,05) apenas para o pH, apesar de todos os valores médios obtidos serem adequados para a conservação da silagem. As estimativas de digestibilidade indicam bom potencial de qualidade para todos os híbridos, especialmente P 3072 e P 3232.<br>A trial was conducted to evaluate forage production and quality of fíve comercial com hybrids (Zea mays) and three sorghum hybrids (Sorghum bicolor). The experimental design was randomized blocks with three replicates. The five com hybrids were: Pioneer 3072 (P 3072), Agroceres 211 (AG 211), Cargill 525 (C 525), Pioneer 3232 (P 3232) and Agroceres 213 (AG 213) and the three sorghum hybrids were: Agroceres 2004 E, 2002 and 2005 E (AG 2004 E, AG 2002 and AG 2005 E, respectively). Plant population was about 50.000 and 160,000 plants/ha for com and sorghum, respectively. The crops were havested at a height of 15cm of soil surface, at grain powdering stage. After the harvested, the forage were ensiled in glass recipients, wich were conserved in a higher silum. The dry matter production of the P 3072 was higher than AG 213 and the three sorghum hybrids. Although all mean value results were adequate for silage conservation and quality, there was only significant difference for pH. The digestibility estimatives show a good quality potential for all hybrids, especially P 3072 and P 3232

Parâmetros genéticos para características de tamanho e condição corporal, eficiência reprodutiva e longevidade em fêmeas da raça Canchim Genetic parameters for body size, condition score, reproductive and longevity traits in females of the Canchim breed

Objetivou-se estimar a herdabilidade das características tempo de permanência no rebanho (TPR) e idades ao primeiro (IDPP), ao segundo (IDSP) e ao terceiro (IDTP) parto e as correlações genéticas entre essas características e os pesos ajustado e não-ajustado para condição corporal, índice de tamanho corporal e condição corporal à primeira monta, ao primeiro parto e à idade adulta. Os componentes de variância e de co-variância foram estimados pelo método de máxima verossimilhança restrita livre de derivadas, utilizando-se análises uni e bicaracterísticas. Os modelos estatísticos incluíram o efeito genético aditivo direto, como aleatório, e o efeito fixo de grupo de contemporâneos. As estimativas de herdabilidade obtidas das análises unicaracterísticas foram 0,10 &plusmn; 0,05 (IDPP); 0,08 &plusmn; 0,05 (IDSP); 0,14 &plusmn; 0,06 (IDTP) e 0,06 &plusmn; 0,00 (TPR), e indicam que provavelmente as características apresentarão baixa resposta à seleção. A seleção para maior peso à idade adulta acarretará redução no tempo de permanência da fêmea no rebanho. A seleção para maiores pesos da fêmea à primeira monta, ao primeiro parto e à idade adulta não deve alterar significativamente as idades ao primeiro, ao segundo e ao terceiro parto. A seleção para os índices de tamanho corporal ou pesos ajustados para condição corporal provavelmente apresentará repostas correlacionadas nas características reprodutivas e de longevidade com tendências semelhantes, mas de maior magnitude em relação à seleção para peso sem ajuste.<br>The objectives of this study were to estimate heritability for culling age (TPR), ages at first (IDPP), at second (IDSP) and at third calving (IDTP) and genetic correlations of these traits with adjusted and unadjusted weights for condition score, body size indexes and condition score at first mating, at first calving and at mature age. Variance and covariance components were estimated by REML using univariate and bivariate models including the fixed effect of contemporary group and additive direct genetic and residual as random effects. Heritability estimates obtained from univariate analyses were 0.10 &plusmn; 0.05 (IDPP), 0.08 &plusmn; 0.05 (IDSP), 0.14 &plusmn; 0.06 (IDTP) and 0.06 &plusmn; 0.00 (TPR) and indicate low response to selection on these traits. Genetic correlation estimates suggest that selection for increasing mature weight will reduce culling age but for heavier weight at first mating, at first calving and at maturity will not significantly change ages at first, at second and at third calving. Selection on body size indexes and on cow weights adjusted for condition score may result in similar correlated responses for reproductive traits and longevity which would be higher than those from selection on unadjusted cow weights